A known apparatus (DE 2 502 866 C2), which is actually provided for curing a still plastic porous concrete block, can also be used to separate the cut porous concrete bodies. The known apparatus has a rectangular base frame with a plurality of horizontal laminae arranged parallel alongside each other and which are movable horizontally in the base frame transverse to their longitudinal direction, a plurality of support pedestals extending upwardly from the laminae and arranged in a row, spaced from one another, on the upper side of each lamina, and a drive device engaging at least at the ends of each lamina, by means of which the laminae can be moved and their mutual spacing be altered. In this known apparatus the laminae extend in the transverse direction of the frame and also in the transverse direction of the rectilinear porous concrete block. After the porous concrete block lying on its base surface has been cut in the transverse direction, so that cut gaps are present, the laminae are pushed together by the drive device, so that the cut gaps are closed up. This is done so that the edges shall not break out in the following longitudinal cutting of the porous concrete block when the cutting wires emerge at each cut gap. After the porous concrete block has also been cut in the longitudinal direction, the laminae are again separated in the longitudinal direction of the frame and also in the longitudinal direction of the porous concrete block, so that the porous concrete bodies are now again separated in the transverse direction of the block also and sticking together of the porous concrete bodies in the hardening is prevented. The separation is only used in this known apparatus when the block, as is only possible in this apparatus, is cut lying down and the cut series of porous concrete bodies are separated in the longitudinal direction of the porous concrete block. The separation is thus effected in a direction in which the porous concrete bodies have a width of 250 mm or a multiple thereof, so that they do not fall over in the separation in the longitudinal direction of the porous concrete block. In the transverse direction of the porous concrete block the porous concrete bodies have a spacing from one another which corresponds to the width of the cutting gap of about 0.8 to 1 mm. This space is indeed enough to prevent sticking together. If however the porous concrete bodies are also to be subjected to a drying operation during steam treatment in the autoclave, as is described in EP 0 133 239 B1 or DE 4 135 119 A1, this spacing is too small to be able to carry out the drying within reasonable time.
In the above-described apparatus, which is also provided for the longitudinal and transverse cutting of the porous concrete block, the porous concrete block is cut lying down, i.e. as it is cast. The length of the wires used for the transverse cutting must then be at least as large as the width of the porous concrete block, which usually amounts to about 1.5 m. Such long cutting wires can deflect to the side in the cutting, so that the accuracy of the cut porous concrete bodies suffers. For this reason it has already been proposed in DE-PS 958 639 to turn the porous concrete block through 90.degree. on to its edge after casting and then to divide it up into porous concrete bodies by cutting wires which are parallel to the shortest edge and are guided vertically and horizontally. This does have the advantage that the cutting accuracy is increased but the cut porous concrete bodies lie on top of one another and can thus stick together in the steam hardening, because of their weight. It is therefore proposed in DE-PS 2 108 300 to turn the cut porous concrete block standing on edge back again through 90.degree. on to its large, wide side (base surface) before it is put in the autoclave. Since however in the longitudinal cutting of the block standing on edge the weight thereof closes up the horizontal cut gaps resulting in the longitudinal cutting and the cut porous concrete slabs are pressed tightly together by the weight, there is also the danger that the porous concrete bodies will stick together even after the turning back again. Moreover the porous concrete bodies lie closely against one another in the transverse direction of the porous concrete block even after the turning back again, so that no hardening steam can get to their facing bounding surfaces. This prolongs the hardening operation and it is also not possible to subject the porous concrete bodies to a drying operation within a reasonable time during the treatment in the autoclave, as is described in EP 0 133 239 B1 or DE 4 135 119 A1.